1. D.J. Herndon et al., report No. LBL 1065/SLAC-PUB-1108, Lawrence Berkeley Laboratory and Stanford Linear Accelerator Center;
2. presented to the XVI Intern. Conf. on High energy physics,1972
3. report No. SLAC-PUB-1257;Cashmore,1973
4. A.H. Rosenfeld, Proc. 1973 Intern. School of Subnuclear physics, Erice, Sicily.